SAF Enilive: the biojet fuel for a more sustainable aviation

SAF (Sustainable Aviation Fuel) is a biofuel produced using the HEFA technology (via the hydrogenation of esters and fatty acids) and can be blended with conventional aviation fuel in proportions of up to 50%. It is made 100% from renewable raw materials, primarily waste and residues such as used cooking oils, animal fat and by-products from vegetable oil processing.

Unlike fossil-based products, biofuels are derived from biogenic raw materials and therefore enable a reduction in GHG emissions, calculated across the entire value chain. Currently, SAFs are the only available solution to contribute to the decarbonization of air transport. Biofuels do not require modifications to aircraft or to the existing fuel distribution infrastructure at airports.

To achieve the goal of more sustainable air transport, SAF producers work in synergy with airlines, engine manufacturers, airport operators and institutions.

At the European level, most European Union member states have set annual increases in biofuel blending targets. Regulation (EU) 2023/2405 stipulates that aviation fuel suppliers must ensure that the jet fuel made available to airline operators at every airport within the European Union contains a proportion of SAF.

In Enilive biorefineries, biofuels (such as SAF and HVO diesel) are produced by subjecting raw materials to a series of physical and chemical processes. Waste, residues and vegetable oils arrive at the biorefineries via ships and tankers and are stored in tanks before undergoing two treatments: a physical one to remove impurities and a chemical one that leads to their actual conversion into biofuels.

During the first treatment, critical components are physically removed from the bio-feedstocks to ensure the efficiency of the Ecofining™ section, whose technology has been developed by Eni in collaboration with Honeywell UOP. Specifically, solid residues and gums (phospholipids) are eliminated through washing and centrifugation in the degumming section, while metals are removed via an adsorption system using bleaching earths in the bleaching section.

The oil obtained, free from metals, gums, and solid residues, then undergoes the second treatment, the chemical process, Ecofining™, which consists of two stages: hydrodeoxygenation, which removes oxygen and residual impurities, including nitrogen, and isomerisation, which converts n-paraffins into isoparaffins with suitable cold-flow properties.

The feedstock used in biorefineries mainly consists of triglycerides and fatty acids, which, through these two stages, are converted into hydrocarbons (isoparaffins), giving the final product properties very similar to fossil-based diesel. Hydrogenation ensures the complete removal of oxygen, whose presence in biogenic products would otherwise promote the formation of bacterial colonies and gums. HVO (Hydrotreated Vegetable Oil) diesel is therefore free from these issues, and it can be used in pure form in diesel engines.

Starting from the end of 2024, by implementing appropriate plant modifications, particularly to the isomerization unit, the tank farm and the logistics facilities, the Gela biorefinery has been integrating SAF production alongside HVO diesel, bio-naphtha, and bio-LPG. In 2026, the production of sustainable aviation fuels will also be extended to the Venice Porto Marghera biorefinery, thanks to a targeted investment plan.